Deep One

The Deep Ones are humanoid beings with fish, human, and amphibian-like traits. In The Shadow Over Innsmouth they are described as having grey-ish green, glossy and slippery skin with white stomachs. They have scaled, ridged backs, as well as webbed hands and gilled necks. Notably, they have a head similar to that of a fish, with eyes incapable of blinking.

They move about in an inhuman fashion, by hopping oddly, and occasionally move on all fours. The narrator, Robert Olmstead, describes them as having abhorrent, croaking voices that spoke a language other than English. Their form was so horrid that their mere appearance caused Robert to lose consciousness.

As part of their pact with the Deep Ones, the residents of Innsmouth are forced to interbreed with them. Although the Deep One hybrid offspring are born with the appearance of a normal human being, they gradually assume the appearance of their Deep One ancestors. These traits include:

When the hybrid becomes too obviously non-human, they go into seclusion in ostensibly abandoned buildings until fully capable of living solely underwater. The rate of progression varies with each individual, however it normally does not reach completion until the human middle age. Once this transformation is complete they are also functionally immortal. Apart from the physical change they also feel a scorn for humanity, an affinity for the Non-euclidean artwork of the Deep One race, and an increasingly powerful desire to abandon the human world and go to the Deep One city of Y'ha-nthlei.